Convertible top with inwardly folding side rails



Oct. 30, 1956 ,L. N. ALBRECHT 2,763,357

CONVERTIBLE TOP WITH INWARDLY FOLDING SIDE RAILS Filed Jan. .16, 1953 6 Sheets-Sheet 1 ATTOR NEYS L. N. ALBRECHT Oct; 30, 1956 CONVERTIBLE TOP WITH INWARDLY FOLDING SIDE RAILS Filed Jan. 16, 1953 6 Sheets-Sheet 2 INVENTOR [armada/hath Y M I ATTORNEYS Oct. 30, 1956 L. N. ALBRECHT 2,768,857

. CONVERTIBLE TOP WITH INWARDLY FOLDING SIDE RAILS Filed Jan. 16, 1953 6 Shets-Sheet s ATTORNEYS -Qct. 30, 1956 L. N. ALBRECHT CONVERTIBLE TOP WITH INWARDLY FOLDING SIDE RAILS I Filed Jan. 16, 1953 6 Sheets-Shae w W M m f o t wry y m A k m w w g M Oct. 30, 1956 N. ALBRECHT 2,768,857

CONVERTIBLE TOP WITH INWARDLY-FOLDING SIDE RAILS 6 Sheets-Sheet 5 Filed Jan. 16, 1953 Oct. 3-0, 1956 L. N. ALBRECHT CONVERTIBLE TOP WITH INWARDLY FOLDING SIDE RAILS Filed Jan. 16, 1953 6 Sheets-Sheet 6 ATTORNEYS United States Patent CONVERTIBLE TOP WITH INWARDLY FOLDING SIDE RAILS Leonard N. Albrecht, Birmingham, Mich., assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application January 16, 1953, Serial No. 331,523

13 Claims. (Cl. 296-117) This invention relates to convertible tops, and more particularly to improved convertible tops for automobiles.

One feature of the invention is that it provides improved convertible tops for automobiles; another feature of the invention is that it provides a convertible top which folds into a stack only a few inches high when the top is lowered; a further feature of the invention .is that novel means are provided for coordinating folding movement of the opposite side rails of the top; still another feature of the invention is that novel means are provided for breaking the side rails upon pivotal movement thereof, this means including meshing bevel gears one of which is stationary on the automobile body and another of which is movable with the folding side rail; yet a further feature of the invention is that it provides a folding top frame having oppositely disposed side rails each formed of rear, center and front sections, together with means for holding the center sections of the side rails parallel to each other when the top is folded; yet another feature of the invention is that it provides a novel movable connection between at least one of the transverse bows and the side rail, providing means for bodily movement between the bow and rail when the top is folded; a further feature of the invention is that it provides means for holding the front bow in proper alignment when the top is being folded and unfolded; and still another feature of the invention is that .it pro vides a novel top which is of the disappearing type and is completely out of sight when lowered.

Other features and advantage of the invention will be apparent from the following description and from the drawings, in which:

Fig. 1 is a fragmentary side elevational view of a convertible automobile having the improved top mounted thereon, portions of the apparatus being shown .in solid lines in one position and in broken lines in another position;

Fig. 2 is an enlarged sectional view taken along the line 2-2 of Fig. 1, showing the means by which each side rail is mounted on the automobile body;

Fig. 3 is a perspective view of the top frame removed from the automobile, the fabric top material being shown only fragmentarily;

Fig. 4 is a view similar to Fig. 3, but with the parts in position to permit raising the top compartment cover to the position shown in broken lines in Fig. 1;

Fig. 5 .is a view similar to Fig. 3 showing the top partially folded;

Fig. 6 is a view similar to Fig. 3 but showing the top almost completely folded;

Fig. 7 is a fragmentary side elevational view, partly in section, of an automobile having a modified top mounted thereon;

Fig. 8 is a perspective view showing the top partially folded;

Fig. 9 is a fragmentary enlarged side elevational view, partly in section, showing the connection of one of the transverse bows to one of the side rail sections;

Fig. 10 is a top plan view, partly broken away, of one of the side rails;

Fig. 11 is an enlarged transverse section taken along the line 11-11 of Fig. 10 and showing the connection of one of the bows to one of the side rail sections;

Fig. 12 is a section taken along the line 12--12 of Fig. l 1; and

Fig. 13 is a view taken from the right of Fig. 11 along the line 13-13.

Referring now more particularly to the drawings, the top shown in Figs. 1 to 6 is designed for a two passenger automobile having only a front seat. While this top is illustrated as being manually operable, it could readily be power operated by any known means, as the power operating means shown in Fig. 7, if desired.

The automobile shown in Fig. 1 has a body 20 provided with a hood 22, a windshield 24, a header bar 26 framing the windshield and a rear deck 28 having therein a compartment 29 for storing the top when it is lowered. This compartment has a cover 30 which is hingedly mounted on the rear deck 28 by means of hinges 32 having springs 34 for automatically raising the cover 30 to open position when a latch 36 is released. When the top is in raised position and also when the top is stored in the compartment, the cover 30 is closed and latched as shown in solid lines in Fig. 1. When the top is to be raised or lowered the latch 36 is released and the springs 34automatically raise the cover 30 to open position.

In order to simplify the drawings, the top frame is shown removed from the automobile in Figs. 3 to 6. The top frame comprises a pair of oppositely disposed side rails, each having a rear section 40 and a front section 42, these sections being pivotally connected at 44 so that the rails break inboard of the body when folded as shown in Figs. 5 and 6.

The rear end of the rear section 40 of each side rail is connected to the automobile body for pivotal movement about a fixed horizontal axis and a movable axis angular to the fixed axis. Mounting bracket 46 and 48 are secured to the body of the automobile and a block member 50, which may be a brass casting, .is pivotally mounted between the brackets and 48 for movement about a fixed horizontal axis 52 formed by shafts 53 and 54. The rear side rail section 40 has welded thereto a bracket 55 on which is rigidly mounted a shaft 56 which extends through the block member 50 and a bevel gear 58 pinned or otherwise rigidly secured thereto adjacent its free end. Shaft 56 is offset to axis 52.

A stationary bevel gear 60 is fixedly mounted on the body by means of a set screw 62 which projects through an opening in the support bracket 48, and the gears 58 and 60 mesh as shown best in Fig. 2. A tie rod 64 extends between the opposite sides of the automobile and is coaxial with the axis 52.

A plurality of transverse bows extend between the opposite side rails and are pivotally connected thereto. At the front end of the front side rail section 42 a front how 66 is mounted, being pivotally connected to each side rail by means of studs 68, and intermediate the ends of the rear side rail section 40 is an intermediate bow 70 connected to the side rail through a link 74 having one end pivotally connected to the rear side rail section 40 and the other end pivotally connected to the end of the bow 70. i

A rear intermediate bow 76 is pivotally connected to an arm 51 on each block member 50 by means of a stud 78 which also provides a pivotal mounting for a rear bow 80. A spring 82 urges the rear how from the position shown in Figs. 1 and 3 upwardly to the position shown in Fig. 4, and counterbalance springs 84 are provided adjacent opposite sides of the automobile for facilitating operation of the top. These counter balance springs are arranged so that they are stretched as the top is lowered, and therefore, exert a counterbalance force through arms 86 to aid in raising the top.

As shown in Fig. 1 and as indicated fragmentarily in Figs. 3 to 6, a fabric top 88 is fastened to the transverse bows 66, 70, 76 and 80.

In order to lower the top from the raised position shown in Figs. 1 and 3, the latch 36 is released to free the how 80 from the cover 30 and to permit the cover 30 to open. Separate latch mechanisms may be provided or the latches may be interconnected as indicated in Fig. l at 911, and be operable through a single release means, as, for example, a pushbutton or any other known latch release. For a detailed disclosure of a latch mechanism which may be used reference is had to the copending application of Jules A. Olivier and William I. Tell, entitled Folding Top Compartment Cover, filed January 13, 1953, Serial No. 330,988 and assigned to the assignee of the present invention.

When the latch means has been released the springs 82 pivot the rear bow 81) from the position of Figs. 1 and 3 to the position of Fig. 4 where it is out of the way of the cover 30, permitting said cover to pivot to the open position of Fig. 1 under the force of spring 34. The front bow 66 is secured to the header bar 26 by any known top latching mechanism, as, for example, a mechanism similar to that shown in the copending application of Irving M. Ziif, entitled Automobile Top Latch, filed December 22, 1952, Serial No. 327,246 now Patent 2,739,012 and assigned to the assignee of the present invention.

After the front bow 66 is released from the header bar, the front bow may manually be pivoted rearwardly, causing the side rails to pivot about the horizontal axis 52. This pivotal movement moves the bevel gears 58 bodily through an arcuate path about the axis 52, and since each bevel gear 58 meshes with one of the stationary bevel gears 60, the bevel gears 58 and the shafts 56 to which they are pinned rotate, causing the side rails to break inwardly at the point of pivotal connection 44 between the front and rear rail sections. The tie rod 64 eliminates any possibility of torque or twisting on opposite sides of the car so that the bevel gears 58 and 60 not only insure that the side rails will break inwardly, but also coordinate the folding movement of the opposite side rails.

As the front bow 66 is moved rearwardly, the top moves successively from the position of Fig. 4 through the positions of Figs. 5 and 6 and folds into a small stack in the compartment 29 in the rear deck 28. When the top is folded, the cover may be closed and latched so that the automobile has the appearance of an open roadster without a top.

Figs. 7 to 13 show a modified convertible top structure which is basically similar to the top of Figs. 1 to 6, but which is intended for use on a five passenger automobile having both front and rear seats.

The top of Figs. 7 to 13 is illustrated as being power operated, and as pointed out earlier, this power operation could also readily be applied to the top of Figs. 1 to 6. The principal differences in the top of Figs. 7 to 13 are: The top does not descend into a compartment which is covered with a metal cover, but the top merely lies in a recess in the rear deck and may be covered with a fabric boot if desired; each side rail is formed of front, center and rear sections in place of the two sections of Figs. 1 to 6; means are provided for holding the center sections in parallel relationship when the top is folded; means are provided for holding the front bow in alignment; and a pivotal and bodily movable connection is provided between one of the transverse bows and the side rails.

The modified convertible top is mounted on an automobile having a body 120 with a hood 122, a windshield 124 framed by a header bar 126, and a rear deck 128 which supports the convertible top when it is folded.

The top frame comprises oppositely disposed side rails,

each formed by a rear section 141), a center section 141 and a front section 142. The rear section 140 is articulated to the center section 141 at 143 and the front section 142 is articulated to the center section 141 at 144, the pivotal connection between the respective side rail sections being such that the rail-s break inboard of the automobile body when folded, as shown in Fig. 8. A support bracket 148 is mounted on each side of the automobile body and the rear end of each rear side rail section is mounted on the body for movement about a fixed horizontal axis and a movable axis which is transverse to the horizontal axis in the same manner as in the top of Figs. 1 to 6.

At each side of the car a block member 159, which may he a brass casting, is pivotally mounted for movement about a fixed horizontal axis 152 formed by shafts similar to shafts 53 and 54 of Fig. 2, mounted in brackets 148 at opposite sides of the automobile body adjacent the back of the rear seat 153. Each rear side rail section 148 is secured to a shaft 156 which extends through a bore in the block member 150 to the opposite side of axis 152 and which is radial thereto. A bevel gear 158 is pinned to shaft 156 and meshes with a stationary bevel gear 169 which is coaxial with axis 152. The structure above described is similar to that shown in Fig. 2 and provides means for insuring that the side rails break inwardly and for coordinating the folding movement of the side rails on opposite sides of the automobile. When the top is moved from raised position toward lowered position by pivoting the side rails about the horizontal axis 152, the bevel gear 158 is swung bodily through an arcuate path about the center of bevel gear 160, and since the gear 158 meshes with gear 160, shaft 156 is rotated about its longitudinal axis, causing the rails to break inwardly. Since the structure is the same on both sides of the automobile body, the folding movement is coordinated and is equal on both sides of the automobile body.

Figs. 7 and 8 show power means for operating the top comprising cylinders 200 pivotally mounted on opposite sides of the automobile body at 201 and each having a piston rod 202 which is articulated to an arm 2193 rigid with the block member 150 so that longitudinal movement of the piston rods 202 pivots the block members 150 and side rail sections 140, 141 and 142 about the horizontal axis 152, moving gear 158 bodily through an arcuate path and causing the shaft 156 to rotate because the movable gear 158 meshes with the stationary gear 160. This rotary motion of shaft 156 breaks the side rails inboard of the automobile body.

The side rails are interconected by a plurality of transverse bows including a from how 166, a front intermediate collapsible bow having a center section 167 and hingedly connected end sections 169, a rear intermediate bow having a center section 170 and end sections 172, and a rear how 176. The collapsible bows are so constructed that they can collapse in one direction only. In each bow the hinges between the center and end sections are on the underside of the bow, and the adjacent end surfaces of the respective center and end sect-ions abut when the bow is extended to form stop means preventing the end sections from being swung upwardly past alignment with the center section. In this construction the top material 188 is permanently secured to the automobile body across the rear thereof, and it is not necessary to have a bow which lies on the rear deck 128 of the automobile when the top is raised.

In order to prevent the side rail sections from becoming cocked or jammed when the top is folded, means are provided for holding the center section 141 of each side rail in parallel alignment with the center section of the opposite side rail while the top is being raised or lowered. This is accomplished by the front intermediate bow which is shown in Figs. 7, 8, 9 and 10 as comprising a wide member having its center and end sections pivotally connected by long-axis piano type hinges 205 and having its end sections 169 connected to the respective side rail center sections 141 by long-axis piano type hinges 207. The provision of a wide bow connected by hinges having long hinging axes prevents the center sections 141 of the side rails from becoming cocked or misaligned, and it may be noted in Fig. 9 that the hinge 207 is supported on the side rail center section 141 by means of four spaced ribs 208, 209, 210 and 211 instead of only a single member of small connectingarea. Fig. 8 shows how the side rail center sections 141 are held in parallel alignment while the top is folded.

Because the side rails are each formed of three pivotally connected sections, it is desirable to provide means for preventing the front bow 166 from being misaligned during opening and closing movements of the top. This means is illustrated in Figs. 9 and 10 as a link having threaded end sections 212 and 214 which are adjustably joined by means of an internally threaded center section 216, the construction being somewhat similar to a turnbuckle in that the length of the link can be adjusted to provide proper alignment of the front bow 166. This rigid link is pivotally connected to the rear side rail section 140 by means of a pin 218 which is spaced from the pivotal connection 143 between the rear and center side rail sections, and the other end of the rigid link is pivotally connected to the front side rail section 142 by means of a pin 220 which is spaced from the pivotal connection 144 so that the front and rear side rail sections are pivotally connected by the rigid link formed of parts 212, 214 and 216, and are also pivotally connected by the center side rail section 141, which in turn is held against angular twisting by the front intermediate bow connections earlier described. This arrangement provides an X type of linkage at each side of the car interconnecting the front and rear side rail sections and preventing the front bow 166 from being cocked out of proper alignment with the header bar 126.

A guided pivotal mounting is provided for the connection between the rear intermediate bow and each rear side rail section 140. This mounting is illustrated in Figs. 11, 12 and 13, wherein it will be seen that the side rail section 140 has a spherical socket 222 in which is mounted an anti-friction ball 224. The socket 222 is formed between a bushing member 226 which is secured to the rear side rail section and a complementary bushing member 228 held together by bolts 230. Each end section 172 of the rear intermediate bow is provided with a solid metal insert 232 having a reduced projecting portion 234 at its free end, the projecting portion 234 extending through an arcuate slot 236 and being secured to the anti-friction ball 224, or, preferably, being turned in one piece integral with ball 224. This construction provides a pivotal and bodily movable connection between the rear intermediate bow and the side rail, and provides means for guiding this pivotal and movable connection as the top frame is being folded or unfolded to facilitate the operation of the collapsible bow.

While I have shown and described two embodiments of my invention, it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made Without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim:

1. In a vehicle body, a folding top frame comprising, a pair of spaced foldable side rails, each of said side rails including a front rail section and a rear rail section, means interconnecting said sections for folding movement thereof, a plurality of transverse bows interconnecting said side rails, means supporting each of said rear rail sections on said body for pivotal movement thereof about a fixed axis and a movable axis transverse to said fixed axis, and means effecting pivotal movement of said rear rail sections about said movable axes to break said side rails inboard with respect to said body upon pivotal movement of said rear rail sections about said fixed axes.

2. In a vehicle body, a folding top frame comprising, a pair of spaced foldable side rails, each of said rails including a front rail section and a rear rail section, means interconnecting said sections for folding movement thereof, a plurality of transverse bows interconnecting said side rails, means supporting each of said rear rail sections on said body for pivotal movement thereof about a fixed horizontal axis extending transversely of said body and a movable axis transverse to said horizontal axis, and means effecting pivotal movement of said rear rail sections about said movable axes to break said side rails inboard with respect to said body upon pivotal movement of said rear rail sections about said fixed axes.

3. In a vehicle body, a folding top frame comprising, a pair of spaced foldable side rails, each of said side rails including a front rail section and a rear rail section, means interconnecting said sections for folding movement thereof, a plurality of transverse bows interconnecting said side rails, means supporting each of said rear rail sections on said body for pivotal movement thereof about a fixed horizontal axis and a movable axis offset and transverse to said fixed axis, and means effecting pivotal movement of said rear rail sections about said movable axes to break said side rails inboard with respect to said body upon pivotal movement of said rear rail sections about said fixed axes. I

4. In a vehicle body, a folding top frame comprising, a pair of spaced foldable side rails, each of said side rails including a front rail section and a rear rail section, means interconnecting said sections for folding movement thereof, a plurality of transverse bows inter' connecting said side rails, means supporting each of said rear rail sections on said body for pivotal movement thereof about a fixed axis and a movable axis transverse to said fixed axis, and means effecting pivotal movement of said rear rail sections about said movable axes to fold said side rails upon pivotal movement of said rear rail sections about said fixed axes, said last mentioned means including first and second meshing gear means, said first gear means being fixed against rotation and said second gear means being fixedly mounted on said rear rail sections coaxially with respect to said movable axes whereby movement of said rear rail sections about said fixed axes causes said second gear means to effect pivotal movement of said rear rail sections about said movable axes by reaction against said first gear means.

5. In a vehicle body, a folding top frame comprising, a pair of spaced foldable side rails, each of said side rails including a front rail section and a rear rail section, means interconnecting said sections for folding movement thereof, a plurality of transverse bows interconnecting said side rails, means supporting each of said rear rail sections on said body for pivotal movement thereof about a fixed axis and a movable axis transverse to said fixed axis, and means effecting pivotal movement of said rear rail sections about said movable axes to fold said side rails upon pivotal movement of said rear rail sections about said fixed axes, said last mentioned means including first and second meshing gear means, said first gear means being coaxial with respect to said fixed axes and fixed against rotation, said second gear means being fixedly mounted on said rear rail sections coaxially with respect to said movable axes whereby movement of said rear rail sections about said fixed axes causes said second gear means to effect pivotal movement of said rear rail sections about said movable axes by reaction against said first gear means.

6. In a vehicle body, a folding top frame comprising,

a pair of spaced foldable side rails, each of said side rails including a front rail section and. a rear rail section, means interconnecting said sections for folding movement thereof, a plurality of transverse bows interconnecting said side rails, means supporting each of said rear rail sections on said body for pivotal movement thereof about a fixed horizontal axis extending transversely of said body and a movable axis transverse to said fixed axis, and means efiecting pivotal movement of said rear rail sections about said movable axes to fold said side rails upon pivotal movement of said rear rail sections about said fixed axes, said last mentioned means including first and second meshing bevel gear means, said first bevel gear means being coaxial with respect to said fixed axis and fixed against rotation, said second bevel gear means being fixedly mounted on said rear rail sections coaxially with respect to said movable axes whereby movement of said rear rail sections about said fixed axis causes said second bevel gear means to effect pivotal movement of said rear rail sections about said movable axes by reaction against said first bevel gear means.

7. In a vehicle body, a folding top frame comprising, a pair of spaced foldable side rails, each of said side rails including a front rail section and a rear rail section, means interconnecting said sections for folding movement thereof, a plurality of transverse bows interconnecting said side rails, means supporting each of said rear rail sections on said body for pivotal movement thereof about a fixed axis and a movable axis transverse to said fixed axis, and means effecting pivotal movement of said rear rail sections about said movable axes to fold said side rails upon pivotal movement of said rear rail sections about said fixed axes, said last mentioned means including first and second meshing gear means, said first gear means being fixed against rotation and said second gear means being fixedly mounted on said rear rail sections coaxially with respect to said movable axes whereby movement of said rear rail sections about said fixed axes causes said second gear means to effect pivotal movement of said rear rail sections about said movable axes by reaction against said first gear means, and power means for moving said rear rail sections about said fixed axes.

8. In a vehicle body, a folding top frame comprising,

'a pair of spaced foldable side rails, each of said side rails including a front rail section and a rear rail section, means interconnecting said sections for folding movement thereof, a plurality of transverse bows interconnecting said side rails, a support member mounted adjacent each side of said body for pivotal movement about a common horizontal axis, means mounting each of said rear rail sections on a respective support member for pivotal movement about an axis transverse to said horizontal axis and movable relative thereto, and means effecting pivotal movement of said rear rail sections about said movable axes to fold said side rails upon pivotal movement of said support members about said horizontal axis, said last mentioned means including first and second meshing gear means, said first gear means being fixed against rotation and said second gear means being fixedly mounted on said rear rail sections coaxially with respect to said movable axes whereby movement of said support members about said horizontal axis causes said second gear means to effect pivotal movement of said rear rail sections about said movable axes by reaction against said first gear means.

9. in a vehicle body, a folding top frame comprising, a pair of spaced foldable side rails, each of said side rails including a front rail section and a rear rail section, means interconnecting said sections for folding movement thereof, a plurality of transverse bows interconnecting said side rails, a support member mounted adjacent each side of said body for pivotal movement about a common horizontal axis, means mounting each of said rear rail sections on a respective support member for pivotal movement about an axis transverse and offset to said horizontal axis and movable relative thereto, and means effecting pivotal movement of said rear rail sections about said movable axes to fold said side rails upon pivotal movement of said support members about said horizontal axis, said last mentioned means including first and second meshing gear means, said first gear means being fixed agm'nst rotation and said second gear means being fixedly mounted on said rear rail sections coaxially with respect to said movable axes whereby movement of said support members about said horizontal axis causes said second gear means to effect pivotal movement of said rear rail sections about said movable axes by reaction against said first gear means.

10. In a vehicle body, a folding top frame comprising a pair of spaced foldable side rails, each of said side rails including front, intermediate, and rear rail sections, means interconnecting said rail sections for folding movement thereof whereby said rails break inboard of said body when folded, means holding each of said intermediate rail sections in substantially parallel relationship when said rails are being folded, means supporting each of said rear rail sections on said body for folding movement of said side rails, and means coordinating folding movement of said spaced foldable side rails.

11. In a vehicle body, a folding top frame comprising a pair of spaced foldable side rails, each of said rails including a front rail section and a rear rail section, means interconnecting said sections for folding movement thereof, a plurality of transverse bows interconnecting said side rails, anti-friction means providing a pivotal and bodily movable connection between at least one of said bows and each of said side rails, and means supporting said rear rail sections on said body for folding movement of said side rails.

12. In a vehicle body, a folding top frame comprising a pair of spaced foldable side rails, each of said side rails including a front rail section and a rear rail section, means interconnecting said rail sections for folding movement thereof, a plurality of transverse bows interconnecting said side rails, anti-friction means providing a pivotal and bodily movable connection between at least one of said bows and each of said side rails, said anti-friction means including an anti-friction ball and socket means in each of said side rails and a projection on said one of said bows engaging each of said balls through an arcuate slot in each of said side rails, said slots guiding bodily movement of said bow relative to each of said side rails, and means supporting each of said rear rail sections on said body for folding movement thereof.

13. In a vehicle body a folding top frame comprising a pair of spaced foldable side rails, each of said side rails including front, intermediate, and rear rail sections, means interconnecting said rail sections for folding movement thereof whereby said rails break inboard of said body when folded, transverse bow means interconnecting said intermediate rail sections, said bow means including a center section and end sections pivotally secured to said center section and a respective intermediate rail section, means holding each of said intermediate rail sections in substantially parallel relationship when said top is folded whereby said end sections of said transverse bow means are foldable toward each other under said center section, and means supporting each of said rear rail sections on said body for folding movement of said side rails.

References Cited in the file of this patent UNITED STATES PATENTS 1,334,381 Kunz Mar. 23, 1920 1,385,138 Lover July 19, 1921 1,789,581 Draper Ian. 20, 1931 2,592,512 Fodermaier Apr. 8, 1952 2,593,360 Sulkowski Apr. 15, 1952 FOREIGN PATENTS 40,609 Denmark July 31, 1929 356,029 Germany July 11, 1922 391,551 Great Britain May 4, 1933 

